1. Technical Fields
This invention generally relates to position sensors and more specifically relates to a high resolution potentiometer placed in a small package.
2. Background Art
Position sensors are widely used in a number of industries to measure the position of various mechanical devices. In particular, position sensors are used in the automobile industry for this purpose. For instance, the position of a driver's seat may be measured and recorded to be recalled later; this allows two or more people to store individual seat positions. As another example, the position of the accelerator pedal may be taken and this position used for various purposes, such as adjusting the throttle. These types of positions can be determined by sensing the angular rotation of a rotor. The farther in angular position the rotor has rotated, the greater the seat inclination or declination, or the faster or slower the driver wishes to go.
Many of these rotary position sensors are made from potentiometers. The position of the wiper on the surface of the potentiometer's resistor and collector tracks determines a voltage. If this voltage is compared to the total voltage across the resistor, a voltage divider may be used to determine the angular position of the rotor. Various conventional devices relate to position sensors. The following examples of patents pertinent to the present invention are hereby incorporated by reference for their pertinent and supportive teachings:
U.S. Pat. No. 4,621,250 to Echasseriau et al. for a rotary sensor, particularly for measuring angular position;
U.S. Pat. No. 4,435,691 to Ginn for a dual track resistor element having nonlinear output;
U.S. Pat. No. 4,430,634 to Hufford et al. for a rotary potentiometer with a molded terminal package;
U.S. Pat. No. 4,643,497 to Oelsch for a device and method for connecting a printed circuit film; and
U.S. Pat. No. 5,828,290 to Buss et al. for a modular position sensor; each of which is herein incorporated by reference for its pertinent and supportive teachings.
Potentiometer sensors such as those described above suffer from several drawbacks. Currently, the resistor and collector tracks are either placed next and parallel to each other, which makes for a deep potentiometer, or are placed along the same line, which makes for a long potentiometer. The tight engine, passenger, and dashboard compartments of today's cars necessitate small sensors, and the current potentiometer sensors are larger than what is convenient.
The relatively large size of potentiometer sensors can be exacerbated by high resolution requirements. Many position sensors in automobiles are required to sense position with a high degree of accuracy. For instance, potentiometers used to determine throttle or accelerator position need to be very accurate. To get this accuracy in potentiometers, the resistor track is generally lengthened. lengthening the resistor track correspondingly makes a relatively large potentiometer even larger.
In addition, some sensors need dual potentiometers for redundancy. In particular, pedal position or throttle sensors in automobiles need redundancy: if only one potentiometer is used and this sensor fails, a potentially dangerous situation may result. By using two potentiometers in these sensors, a failure of one sensor should avoid a potentially catastrophic situation because the second sensor may not fail and may thus still be used to sense throttle position. Using dual potentiometers in one sensor creates an even larger sensor that must fit in cramped automobile spaces.
Thus, without a way to make potentiometers smaller while retaining high resolution and possibly redundancy, potentiometer sensors will be larger than ideal and will be hard to fit into cramped spaces.
The foregoing patents reflect the most relevant state of the art of which the applicants are aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information that may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.